I could see that working, but I think you'll find DPS lagging a bit - also you'll miss out on some greater area dmg coverage nodes. Maybe that's okay to balance out some better survivability.

I'm reading lots of comments FT begins to scale poorly at high levels (I'm not seeing it at all at lvl 50), so maybe you could consider balancing out some other added DPS option. 4-6L flame trap in Searing Touch + 4-6L Flame Blast (maybe with mana + life leech?) in the chest to pick off those that don't die quickly. FB benefits from many/all of FT's node choices.

I'm level 87 in Ambush, Gear posted below, spec is my own variant (taken from old tree and modified slightly with buff to spell damage in 1.1) and I absolutely 1 shot everything in all maps with crazy mods (posting a few example maps below that this build absolutely destroys).

Things to note regarding gear:

1. I don't double curse. I use Flammability on my Searing Touch 6s (It gets +2 as well from the staff). I use movement speed as a defense and while I have a pair of Windscream Greaves I never use them. Also the ring is meh.

I have been on the lookout for a neck with +1 additional curse but I want one with good stats not one that is garbage. I've also found that the Atziri neck is amazing for this build and I've been using it since day 2 of the league.

2. I'm playing with the Sunblast belt. My main belt (also linked) is much better for defenses.

3. Also not sold on the 800+ armour helm. I've posted my old one below

4. All gems in my Carcass Jack are for group play except Decoy totem. We run 4-6 man parties every night and we have an insane CoC player so I curse CW for him when we group. Typically in groups I'll swap in the Windscreams and curse Ele Weakness as well but again I REALLY hate the movement speed loss.

5. CWDT setup is meh. Might replace MS with Increased Duration or something. Also might level it up to 11ish.

6. Going to change spec tonight to pick up some aura passive nodes (similar to update in op) and see if I can squeeze determination in this setup.

Feel free to whisp me in game with any questions. Here is what I'm running